1. Field of the Invention
The present invention relates to a driver in silicon on insulator (SOI) technology for a plasma display panel (PDP).
2. Discussion of the Related Art
Flat Panel Displays (FPDs) are thin, flat electronic devices used for displaying alphanumeric information, graphics, and images. FPDs have increased in performance and capability dramatically over the past decade, so that the most advanced FPDs now are capable of displaying full-color, high definition images at full video rates. A number of different technologies are used for making FPDs. These technical approaches have different characteristics, with differing strengths and weaknesses. The dominant flat panel display technology is the active matrix liquid crystal display (AMLCD).
PDPs incorporate the same xe2x80x9ctwisted nematicxe2x80x9d effect and color filters used in AMLCDs. The only difference is that instead of having a transistor associated with each pixel, the PALC display uses plasma discharges to control the liquid crystal. Despite an inherently lower cost to manufacture, plasma display panels (PDPs) have relatively high power consumption, high operating voltage, and low color brightness in comparison to LCDs. If these deficiencies can be addressed successfully, plasma technology has the potential for a larger market share. Computer displays, primarily for portable personal computers, are the largest single commercial market. Undeniably, today""s laptop computers were primarily enabled by the flat panel display. In addition to the computer market, there are a broad range of other commercial applications particularly in applications requiring large-area including vehicle displays (aviation cockpits, automobile dashboards and navigation displays), personal digital assistants, video telephones, medical systems, and high definition and high resolution, full motion video (including HDTV). Much of the demand today for plasma displays is in the business and commercial, industrial equipment, and military markets. They compete with Electroluminescent Displays (ELDs) for use in ticketing machines and financial terminals and with vacuum florescent displays (VFDs) for process control equipment and medical instruments.
PDP applications in commercial and military information technology enable a vast new range of flat panel displays (FPDs)xe2x80x94Millimeters deep, weighing well under a pound, rugged enough for avionics, and completely portable panels are currently being developed. The advantages of PDPs over AMLCDs include: brighter picture, wider viewing angle, better color purity, and higher contrast ratio.
The largest FPDs available are plasma display panels. Plasma Display Panels are large, flat and thin displays on which a picture is created between two glass plates. The front plate contains horizontal pairs of electrodes called sustain and scan electrodes. In each of the one million pixels light is generated by a small ionized gas (usually noble) discharge between the plates. Depending upon the type of gas used, various colors can be generated. In a monochrome display the light from the gas discharge is that which is seen on the display. However, to obtain a multicolor display, phosphors are required. The plasma panel uses a gas discharge at each pixel to generate ultraviolet radiation that excites the particular phosphor that is located at each pixel. A certain trigger (or priming) voltage is required to start the ionization process, after which the process will continue at a lower voltage and the brightness of the emission will depend directly upon the current passing through the ionized gas, known as a plasma. The predominant technology is an AC driven display that obtains color by using the ultraviolet emission from a combination of Hexe2x80x94Krxe2x80x94Xe or Ne gases to excite red, green and blue phosphors. Focal points are addressing schemes and picture processing with the goals of lowering the costs and improving the picture quality. Such are particularly useful for producing a large moving picture, which looks like a painting on the wall.
The sustaining and scanning functions are performed separately in panels available today. Integrated circuits exist for scan functions, for example STV7697A, made by STMicroelectronics, but sustain functions are performed with discrete high voltage components or hybrid thin-film circuits. Opto-couplers or gate-driving circuits with external components (capacitors and bootstrap diodes) are required to drive these discrete transistors.
Since PDPs require a high voltage potential and are mostly capacitive, an energy recovery circuit is required. Moreover, the inductor lowers electromagnetic interference (EMI) by making the high-voltage and high-current signal transitions less abrupt. In contrast with LCDs, no inductor is needed because the energy is lower. Energy recovery methods are used to recycle the energy in the panel capacitance. Weber et al. (U.S. Pat. Nos. 4,866,349 and 5,081,400) and Sano et al. (U.S. Pat. No. 5,994,929) topologies are the most common. Weber uses an inductor and a capacitor, two transistors, two diodes, and separate drivers. For properly addressing the panel, extra transistors are needed for each panel rows. Weber sustains the panel through these high-voltage scan transistors. The sustain current flows through each scan device and unused power is dissipated, which further results in a drop in sustain voltage.
The prior art uses discrete components and a special IC to control the gate drivers or circuits on the printed circuit board. A disadvantage of the prior art PDP is the large number of components on the board.
Despite the significant advantages afforded by the PDP, there is still a desire to reduce the number of components, and therefore, reduce the cost.
Accordingly, the present invention is directed to a combined scan/sustain driver for a plasma display panel using dynamic gate drivers in SOI technology that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An advantages of the present invention is to provide a new driver for a plasma display panel that can perform both the scanning and sustaining of individual lines. The integrated circuit is adapted to integrated fabrications and allows scanning as well as sustaining with the same circuit. The circuit allows multiple rows to be scanned individually while being able to sustain multiple rows with the same drivers using a single inductor.
Another advantage of the present invention is that the gate drivers do not require external components to level-shift the control signals. The drivers can be paralleled and used to sustain multiple lines using a single inductor for energy recovery.
The integration of both the scanning and sustaining functions in one chip without external components for level shifting (gate driving) can decrease the cost of fabrication and increase the performance of plasma display panels.
The main characteristics of the PDP scan/sustain driver include: single row design for scan that can be paralleled for sustain with single inductor; control via 5 volts logic; variable driving strength level shifters; and produces less than 5 volts drop during 500 mA output current plasma discharge.
Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from that description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a scan/sustain driver circuit for a plasma display panel, comprises a chip including at least three gate drivers, wherein each gate driver has at least one high selector and at least one low selector for digital logic control; at least four high voltage N-type transistors; at least two high voltage diodes; at least two zener diodes; a low voltage buffer having at least one low selector; and an energy recovery circuit provided external to the chip; wherein at least one of the at least four high voltage N-type transistors is connected to a voltage supply of about 200 volts; and wherein at least one of the at least four high voltage N-type transistors is connected to ground.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.